1Tcl_SubstObj(3) Tcl Library Procedures Tcl_SubstObj(3)
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8 Tcl_SubstObj - perform substitutions on Tcl values
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11 #include <tcl.h>
12 Tcl_Obj *
14 Tcl_SubstObj(interp, objPtr, flags)
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17 Tcl_Interp *interp (in) Interpreter in which to execute Tcl
18 scripts and lookup variables. If an
19 error occurs, the interpreter's
20 result is modified to hold an error
21 message.
22 Tcl_Obj *objPtr (in) A Tcl value containing the string to
24 perform substitutions on.
25 int flags (in) ORed combination of flag bits that
27 specify which substitutions to per‐
28 form. The flags TCL_SUBST_COMMANDS,
29 TCL_SUBST_VARIABLES and
30 TCL_SUBST_BACKSLASHES are currently
31 supported, and TCL_SUBST_ALL is pro‐
32 vided as a convenience for the com‐
33 mon case where all substitutions are
34 desired.
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38 The Tcl_SubstObj function is used to perform substitutions on strings
39 in the fashion of the subst command. It gets the value of the string
40 contained in objPtr and scans it, copying characters and performing the
41 chosen substitutions as it goes to an output value which is returned as
42 the result of the function. In the event of an error occurring during
43 the execution of a command or variable substitution, the function
44 returns NULL and an error message is left in interp's result.
45 Three kinds of substitutions are supported. When the TCL_SUBST_BACK‐
47 SLASHES bit is set in flags, sequences that look like backslash substi‐
48 tutions for Tcl commands are replaced by their corresponding character.
49 When the TCL_SUBST_VARIABLES bit is set in flags, sequences that look
51 like variable substitutions for Tcl commands are replaced by the con‐
52 tents of the named variable.
53 When the TCL_SUBST_COMMANDS bit is set in flags, sequences that look
55 like command substitutions for Tcl commands are replaced by the result
56 of evaluating that script. Where an uncaught “continue exception”
57 occurs during the evaluation of a command substitution, an empty string
58 is substituted for the command. Where an uncaught “break exception”
59 occurs during the evaluation of a command substitution, the result of
60 the whole substitution on objPtr will be truncated at the point immedi‐
61 ately before the start of the command substitution, and no characters
62 will be added to the result or substitutions performed after that
63 point.
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66 subst(n)
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69 backslash substitution, command substitution, variable substitution
70Tcl 8.4 Tcl_SubstObj(3)